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Methadone Dosing Calculator

Pain Management - Opioid Conversions

Factors that must be addressed during the conversion process include: Age of the patient or presence of coexisting conditions. Use additional caution with elderly patients (65 years and older), and in patients with liver, renal, or pulmonary disease.

Please review these important points:

  1. Published equianalgesic ratios are considered crude estimates at best and therefore it is imperative that careful consideration is given to individualizing the dose of the selected opioid. Dosage titration of the new opioid should be completed slowly and with frequent monitoring. 
  2. Conversion ratios in many equianalgesic dosing tables do not apply to repeated doses of opioids.
  3. The amount of residual drug in the patient's system must be accounted for. Example: fentanyl will continue to be released from the skin 12 to 36 hours after removal of the patch. Residual effects from discontinued long-acting formulations should also be assessed before converting a patient to a new opioid.
  4. Review the concept of incomplete cross-tolerance:
  5. D. McAuley:   "Incomplete cross-tolerance relates to tolerance to a currently administered opiate that does not extend completely to other opioids. This will tend to lower the required dose of the second opioid. This incomplete cross-tolerance exists between all of the opioids and the estimated difference between any two opiates could vary widely. This points out the inherent dangers of using an equianalgesic table and the importance of viewing the tabulated data as approximations. Many experts recommend - depending on age and prior side effects - reducing the dose of the new opiate by 33 to 50 percent to account for this incomplete cross-tolerance. (Example: a patient is receiving 200mg of oral morphine daily (chronic dosing), however, because of side effects a switch is made to oral hydromorphone 25 - 35mg daily - (this represents a 33 to 50 percent reduction in dose compared to the calculated 50mg conversion dose produced via the equianalgesic calculator). This new regimen can then be re-titrated to patient response. In all cases, repeated comprehensive assessments of pain are necessary in order to successfully control the pain while minimizing side-effects."
  6. The use of high but ineffective doses of a previous opioid may result in overestimation of the converted opioid. 
  7. Ideally, methadone conversions (especially patients who were previously receiving high doses of an opioid) should only be attempted in cooperation with a pain specialist or a specialist in palliative medicine. 

Converting From:

Codeine (PO) (Total daily dose in mg)
Fentanyl (IM/IV) 
[ ? ]Additional options available near the bottom of the page.
(Total daily dose in mcg)
Fentanyl (Transdermal)
[ ? ]Additional options available near the bottom of the page.
Hydrocodone (PO) (Total daily dose in mg)
Hydromorphone (IV/IM/SC) (Total daily dose in mg)
Hydromorphone (PO) (Total daily dose in mg)
Morphine (IV/IM/SC) (Total daily dose in mg)
MORPhine (PO) (Total daily dose in mg)
Oxycodone (PO) (Total daily dose in mg)
OxyMORPHone (IV/IM/SC) (Total daily dose in mg)
Oxymorphone (PO) (Total daily dose in mg)
Tapentadol (PO) (Total daily dose in mg)
Tramadol (PO) (Daily dose in mg)
Reduction for incomplete cross tolerance:   

[ ? ]Additional conversion options below. See reference notations for additional guidance if needed.

The authors make no claims of the accuracy of the information contained herein; and these suggested doses and/or guidelines are not a substitute for clinical judgment. PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.  
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Advanced options (optional)

Review only if converting 'TO' chronic oral methadone

Modify the factors below based on your local protocols.
Morphine equivalents | Methadone factor
0-99 mg: 100-299 mg:
300-499 mg: 500-999 mg:
1000-1999 mg: geq2000 mg:
Default factors are based on the following references:2,9,10,12

Review if converting 'FROM' or 'TO' I.V. or transdermal fentanyl

Converting FROM fentanyl patch:   Converting TO fentanyl patch: [ignore]
Converting FROM IV fentanyl:      Converting TO IV fentanyl:   [ignore]


Equianalgesic dosage table
Buprenorphine (IM/IV): 0.4
Butorphanol (IM/IV): 2.0
Codeine (IM/IV): 120
Codeine (PO): 200
Fentanyl (IM/IV): 0.1
Fentanyl (Transdermal): 0.2
Hydrocodone (PO): 30
Hydromorphone (IV/IM/SC): 1.5
Hydromorphone (PO): 7.5
Levorphanol (acute PO): 4.0
Levorphanol (chronic PO): 1.0
Meperidine (IV/IM/SC): 75
Meperidine (PO): 300
Methadone (acute IV): 5.0
Methadone (acute PO): 10
Methadone (chronic PO): see table above
Morphine (IV/IM/SC): 10
Morphine (acute PO): 60
Morphine (chronic PO): 30
Nalbuphine (IV/IM/SC): 10
Oxycodone (PO): 20
Oxymorphone (IV/IM/SC): 1.0
Oxymorphone (PO): 10
Tapentadol (PO): 75-100
Additional conversion data
  1. American Pain Society (APS). Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain, 6th edition. 2008. Glenview, IL 60025.
  2. Ayonrinde OT, Bridge DT. The rediscovery of methadone for cancer pain management. Med J Aust 2000; 173(10): 536-540.
    Daily oral morphine dose equivalents Conversion ratio of oral morphine to oral methadone
    <100 mg 3:1
    101-300 mg 5:1
    301-600 mg 10:1
    601-800 mg 12:1
    801-1000 mg 15:1
    >1000 mg 20:1
  3. Breitbart W, Chandler S, Eagel B, et al. An alternative algorithm for dosing transdermal fentanyl for cancer-related pain. Oncology. 2000;14:695-705.
  4. Donner B, et al. Direct conversion from oral morphine to transdermal fentanyl. Pain. 1996; 64:527-534.
  5. Duragesic® Package Insert: Accessed: October 2010.
  6. Fisch MJ, Cleeland CS: Managing cancer pain. In: Skeel RT, ed.: Handbook of Cancer Chemotherapy. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2003, pp 663.
  7. Friedman LL, Rodgers PE. Pain management in palliative care. Clin Fam Prac. 2004;6:371-393.
  8. Fudin J, Marcoux MD, Fudin JA. Mathematical Model For Methadone Conversion Examined. Practical Pain Management. 2012(Sep):46-51.
  9. Gazelle G, Fine PG. Fast Facts Documents #075 - Methadone for the Treatment of Pain, 2nd ed 2009. End of Life/ Palliative Education Resource Center. Link: April 2013).
    "Due to incomplete cross-tolerance, it is recommended that the initial dose is 50-75% of the equianalgesic dose" - Based on the Ayonrinde method above.
    Daily oral morphine dose equivalents Conversion ratio of oral morphine to oral methadone using 25% reduction (75% of equianalgesic dose)
    <100 mg 4:1
    101-300 mg 6.7:1
    301-600 mg 13.3:1
    601-800 mg 15.4:1
    801-1000 mg 20:1
    >1000 mg 26.7:1
  10. Methadone PI (package insert). Dolophine hydrochloride, 5 mg, 10mg tablets. July 2012.
    Oral Morphine to Oral Methadone Conversion for Chronic Administration (Package Insert versus GlobalRPh default factors)
    Total Daily Baseline Oral Morphine Dose Estimated Daily Oral Methadone Requirement as % of Total Daily Morphine Dose
    < 100 mg 20% to 30%
    [Globalrph 25% (4:1)]
    100 to 300 mg 10% to 20%
    [Globalrph 12.5% (8:1)]
    300 to 600 mg 8% to 12%
    [Globalrph (300-499) 8.3% (12:1)]
    600 mg to 1000 mg 5% to 10%
    [Globalrph (500-999) 6.66% (15:1)]
    > 1000 mg < 5 %
    [Globalrph (>1000) 5% (20:1) ]
  11. McPherson ML. Demystifying opioid conversion calculations. A guide for effective dosing. Bethesda: American Society of Health System Pharmacists;2010.
  12. Mercadante S, Casuccio A, Fulfaro F, et al. Switching from morphine to methadone to improve analgesia and tolerability in cancer patients: A prospective study. J Clin Oncol. 2001;19:2898-2904.
    30-90 mg 4:1
    90-300 mg 8:1
    > 300 mg 12:1
  13. Morley J, Makin M. The use of methadone in cancer pain poorly responsive to other opiates. Pain Rev.1998;5:51-58.
  14. Ripamonti C, Groff L, Brunelli C, Polastri D, Stavrakis A, De Conno F. Switching from morphine to oral methadone in treating cancer pain: what is the equianalgesic dose ratio? J Clin Oncol. 1998;16(10):3216-3221.
  15. Rosenquist EW. Overview of the treatment of chronic pain. In: UpToDate, Aronson MD (Ed), UpToDate, Waltham, MA. (Accessed on January 15, 2015.)

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